Blues, Boogie, & Bop: The 1940s Mercury Sessions is an eclectic seven-CD set of rarities by everyone from Buddy Rich (drumming and singing) to jump-blues man Eddie ''Cleanhead'' Vinson. Treats include early work by R&B pianist Professor Longhair and blues shouter Jimmy Witherspoon, but alternate takes of Albert Ammons' boogie-woogie pieces are too much of a good thing.

